Tree ring dating history

“Variations in atmospheric radiocarbon concentration are largely the result of carbon dioxide emissions from activity from volcanoes and the ocean, but they are also influenced by changes in solar activity,” explains Oxford University archaeologist Michael Dee, lead author of the study. Such markers can be easily identified in known-age tree-rings and are fixed in time.” According to the researchers, archaeologists have been forced to rely on relatively sparse evidence to date the history of Western civilization before 763 B. In addition to being imprecise, dating archaeological finds by comparing the ratio between two isotopes of the element carbon—slowly decaying carbon-14 and stable carbon-12—in organic materials is expensive. Another potential obstacle is that it’s uncertain just how often intense bursts of solar radiation have struck the Earth.

An additional problem with carbon-14 dates from archeological sites is known as the "old wood" problem.

It is possible, particularly in dry, desert climates, for organic materials such as from dead trees to remain in their natural state for hundreds of years before people use them as firewood or building materials, after which they become part of the archaeological record.

Carbon-14 moves up the food chain as animals eat plants and as predators eat other animals. It takes 5,730 years for half the carbon-14 to change to nitrogen; this is the half-life of carbon-14.

After another 5,730 years only one-quarter of the original carbon-14 will remain.

That means radiocarbon spikes could be found not just in timbers used to construct ancient buildings but in reeds used to make papyrus and baskets and flax woven into linen. Scientists have been forced to use ancient records of rare astronomical phenomena, such as solar eclipses, to date historical events. Even a handful of these time-markers would improve the dating framework for ancient civilizations, they say.

Scientists who spotted a radiation signature of a solar storm in an ancient object made from an organic material would be able to precisely date the artifact as well as historical events connected with it. were almost vertical and of comparable magnitude all around the Earth. And even with high-tech tools such as radiocarbon dating, the best that scholars can often do is date objects and events to within a range of 50 to 100 years or more. One challenge facing scientists is that tree-ring data are only available in 10-year blocks not year-by-year, so the study’s authors have proposed the adoption of a new science called “astrochronology” to mine solar storm data through the use of advance mathematics to re-examine existing tree-ring data.

The relatively short half-life of carbon-14, 5,730 years, makes the reliable only up to about 50,000 years.